Acids are complex substances whose molecules include hydrogen atoms that can be replaced or exchanged for metal atoms and an acid residue.

Based on the presence or absence of oxygen in the molecule, acids are divided into oxygen-containing(H 2 SO 4 sulfuric acid, H 2 SO 3 sulfurous acid, HNO 3 nitric acid, H 3 PO 4 phosphoric acid, H 2 CO 3 carbonic acid, H 2 SiO 3 silicic acid) and oxygen-free(HF hydrofluoric acid, HCl hydrochloric acid (hydrochloric acid), HBr hydrobromic acid, HI hydroiodic acid, H 2 S hydrosulfide acid).

Depending on the number of hydrogen atoms in the acid molecule, acids are monobasic (with 1 H atom), dibasic (with 2 H atoms) and tribasic (with 3 H atoms). For example, nitric acid HNO 3 is monobasic, since its molecule contains one hydrogen atom, sulfuric acid H 2 SO 4 – dibasic, etc.

There are very few inorganic compounds containing four hydrogen atoms that can be replaced by a metal.

The part of an acid molecule without hydrogen is called an acid residue.

Acidic residues may consist of one atom (-Cl, -Br, -I) - these are simple acidic residues, or they may consist of a group of atoms (-SO 3, -PO 4, -SiO 3) - these are complex residues.

In aqueous solutions, during exchange and substitution reactions, acidic residues are not destroyed:

H 2 SO 4 + CuCl 2 → CuSO 4 + 2 HCl

The word anhydride means anhydrous, that is, an acid without water. For example,

H 2 SO 4 – H 2 O → SO 3. Anoxic acids do not have anhydrides.

Acids get their name from the name of the acid-forming element (acid-forming agent) with the addition of the endings “naya” and less often “vaya”: H 2 SO 4 - sulfuric; H 2 SO 3 – coal; H 2 SiO 3 – silicon, etc.

The element can form several oxygen acids. In this case, the indicated endings in the names of acids will be when the element exhibits a higher valence (the acid molecule contains a high content of oxygen atoms). If the element exhibits a lower valency, the ending in the name of the acid will be “empty”: HNO 3 - nitric, HNO 2 - nitrogenous.

Acids can be obtained by dissolving anhydrides in water. If the anhydrides are insoluble in water, the acid can be obtained by the action of another stronger acid on the salt of the required acid. This method is typical for both oxygen and oxygen-free acids. Oxygen-free acids are also obtained by direct synthesis from hydrogen and a non-metal, followed by dissolving the resulting compound in water:

H 2 + Cl 2 → 2 HCl;

H 2 + S → H 2 S.

Solutions of the resulting gaseous substances HCl and H 2 S are acids.

Under normal conditions, acids exist in both liquid and solid states.

Chemical properties of acids

Acid solutions act on indicators. All acids (except silicic) are highly soluble in water. Special substances - indicators allow you to determine the presence of acid.

Indicators are substances of complex structure. They change color depending on their interaction with different chemicals. In neutral solutions they have one color, in solutions of bases they have another color. When interacting with an acid, they change their color: the methyl orange indicator turns red, and the litmus indicator also turns red.

Interact with bases with the formation of water and salt, which contains an unchanged acid residue (neutralization reaction):

H 2 SO 4 + Ca(OH) 2 → CaSO 4 + 2 H 2 O.

Interact with base oxides with the formation of water and salt (neutralization reaction). The salt contains the acid residue of the acid that was used in the neutralization reaction:

H 3 PO 4 + Fe 2 O 3 → 2 FePO 4 + 3 H 2 O.

Interact with metals. For acids to interact with metals, certain conditions must be met:

1. the metal must be sufficiently active with respect to acids (in the series of activity of metals it must be located before hydrogen). The further to the left a metal is in the activity series, the more intensely it interacts with acids;

2. the acid must be strong enough (that is, capable of donating hydrogen ions H +).

When chemical reactions of acid with metals occur, salt is formed and hydrogen is released (except for the interaction of metals with nitric and concentrated sulfuric acids):

Zn + 2HCl → ZnCl 2 + H 2 ;

Cu + 4HNO 3 → CuNO 3 + 2 NO 2 + 2 H 2 O.

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Abstract on the topic:

Hydrogen iodide

Plan:

Introduction

• 1 Receipt
• 2 Properties
• 3 Application
Literature

Introduction

Hydrogen iodide HI is a colorless, asphyxiating gas that smokes strongly in air. It is highly soluble in water, forms an azeotropic mixture with a boiling point of 127 °C and a HI concentration of 57%. Unstable, decomposes at 300 °C.

1. Receipt

In industry, HI is obtained by the reaction of iodine with hydrazine:

2 I 2 + N 2 H 4 → 4 HI + N 2

In the laboratory, HI can be obtained using redox reactions:

• H 2 S + I 2 → S↓ + 2HI
• PI 3 + 3H 2 O → H 3 PO 3 + 3HI

Hydrogen iodide is also produced by the interaction of simple substances. This reaction occurs only when heated and does not proceed to completion, since equilibrium is established in the system:

H 2 + I 2 → 2 HI

2. Properties

An aqueous solution of HI is called hydroiodic acid(colorless liquid with a pungent odor). Hydroiodic acid is a strong acid. Salts of hydroiodic acid are called iodides. 132 g of HI dissolves in 100 g of water at normal pressure and 20ºC, and 177 g at 100ºC. 45% hydroiodic acid has a density of 1.4765 g/cm 3 .

Hydrogen iodide is a strong reducing agent. When standing, an aqueous solution of HI turns brown due to its gradual oxidation by atmospheric oxygen and the release of molecular iodine:

4HI + O 2 → 2H 2 O + 2I 2

HI is capable of reducing concentrated sulfuric acid to hydrogen sulfide:

8HI + H 2 SO 4 → 4I 2 + H 2 S + 4H 2 O

Like other hydrogen halides, HI adds to multiple bonds (electrophilic addition reaction):

HI + H 2 C=CH 2 → H 3 CCH 2 I

During the hydrolysis of iodides of some metals of lower oxidation states, hydrogen is released: 3FeI 2 + 4H 2 O → Fe 3 O 4 + 6HI + H 2

Alkaline iodides have the following properties: Index NaI KI NH 4 I Density g/cm3 3.67 3.12 2.47 Melting point ºC 651 723 557 (sublimation) Solubility 20ºC 178.7 144 172.3 Solubility 100ºC 302 200 250.2 Density 37.5% solution 1.8038 1.731 Solubility: g per 100 g of water

Under the influence of light, alkali salts decompose, releasing I 2, which gives them a yellow color. Iodides are obtained by reacting iodine with alkalis in the presence of reducing agents that do not form solid by-products: formic acid, formaldehyde, hydrazine: 2K 2 CO 3 + 2I 2 +HCOH → 4KI + 3CO 2 + H 2 O Sulfites can also be used, but they contaminate the product sulfates. Without the addition of reducing agents, when preparing alkali salts, MIO 3 iodate is formed along with iodide (1 part to 5 parts of iodide).

Cu 2+ ions, when interacting with iodides, easily give poorly soluble salts of monovalent copper CuI: 2NaI + CuSO 4 + Na 2 SO 3 + H 2 O → 2CuI + 2Na 2 SO 4 + H 2 SO 4 [Ksenzenko V. I., Stasinevich D . S. “Chemistry and technology of bromine, iodine and their compounds” M., Chemistry, 1995, −432 pp.]

3. Application

Hydrogen iodide is used in laboratories as a reducing agent in many organic syntheses, as well as for the preparation of various iodine-containing compounds.

Alcohols, halides and acids are reduced with HI, giving alkanes [Nesmeyanov A.N., Nesmeyanov N.A. “Beginnings of Organic Chemistry Vol. 1” M., 1969 p. 68]. BuCl + 2HI → BuH + HCl + I 2 When HI acts on pentoses, it converts them all into secondary amyl iodide: CH2CH2CH2CHICH3, and hexoses into secondary n-hexyl iodide. [Nesmeyanov A. N., Nesmeyanov N. A. “Principles of organic chemistry vol. 1” M., 1969 p. 440]. Iodine derivatives are most easily reduced; some chlorine derivatives are not reduced at all. Tertiary alcohols are the easiest to reduce. Polyhydric alcohols also react under mild conditions, often yielding secondary iodoalkyls. ["Preparative organic chemistry" M., State. n.t. chemical publishing house Literary, 1959 p. 499 and V.V. Markovnikov Ann. 138, 364 (1866)].

HI decomposes quickly in light. Reacts with atmospheric oxygen, giving I2 and water. Concentrated sulfuric acid also oxidizes HI. Sulfur dioxide, on the contrary, reduces I 2: I 2 + SO 2 +2H 2 O → 2 HI + H 2 SO 4

When heated, HI dissociates into hydrogen and I 2, which makes it possible to produce hydrogen with low energy costs.

Literature

• Akhmetov N. S. “General and inorganic chemistry” M.: Higher School, 2001

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This abstract is based on an article from Russian Wikipedia. Synchronization completed 07/13/11 23:37:03
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It is colorless and mixes easily with water. One hundred milliliters of liquid contains 132 grams of hydrogen iodide. This is at normal pressure and room temperature. When heated to 100 degrees, 177 grams already dissolve in water. Let's find out what the resulting solution is capable of.

Properties of hydroiodic acid

Being strong, the connection manifests itself as typical. This is expressed, for example, in reactions with. Interaction takes place with those of them that are to the left. It is in the place of this element that the atom takes place.

It turns out to be iodite. Hydrogen evaporates. With salts hydroiodic acid reacts also in case of gas evolution. Less commonly, the interaction results in the precipitation of one of its products.

The heroine of the article also reacts with basic oxides, like other strong ones. Basic oxides are compounds with oxygen of metals with the first or second oxidation states. The reaction results in the release of water and the production of iodite, that is, hydroiodic acid salts.

The reaction of the heroine with bases also gives water and. Typical interaction for strong people. However, most substances are tribasic. This indicates the content of 3 hydrogen atoms in the molecule.

In the hydrogen iodide compound there is only one gas atom, which means the substance is monobasic. In addition, it is oxygen-free. As hydrochloric acid is written as HCl, so hydroiodic acid formula– HI. Essentially, it is gas. What to do with an aqueous solution? It is considered true, but is rarely found in laboratories. The problem is storing the solution.

Strong restorative properties of hydroiodic acid lead to rapid oxidation. As a result, pure water and a brown sediment remain at the bottom of the test tube. This is iodine diodoiodate. That is, the heroine is short-lived in solution.

The process of “damage” is inevitable. But, there is a way to restore the heroine of the article. They do this using . distilled in his presence. An inert atmosphere is needed, for example, argon or carbon dioxide.

An alternative to phosphorus is hydrogen dixodihydrogen phosphate with the formula H (PH 2 O 2). The presence of hydrogen sulfide during distillation also has a positive effect on hydrogen iodide. Therefore, you should not throw away the separated mixture and mix fresh reagents. can be restored.

Until the iodine in the solution has oxidized, the liquid is colorless and has a strong odor. The solution is azeototropic. This means that when boiling, the composition of the mixture remains the same. The evaporation and liquid phases are in equilibrium. Hydroiodine boils, by the way, not at 100, but at 127 degrees Celsius. If heated to 300 degrees, the substance will decompose.

Now, let’s find out why hydrogen iodide is considered the strongest among the strong ones. An example of interaction with “colleagues” is enough. Thus, when hydrogen iodide “meets” sulfuric concentrate, it reduces it to hydrogen sulfide. If a sulfur compound meets with others, it will act as a reducing agent.

The ability to donate hydrogen atoms is the main property. These atoms combine with other elements to form new molecules. This is the recovery process. Restoration reactions are also the basis for receiving the heroine of the article.

Preparation of hydroiodic acid

Due to instability, the hydrogen iodide compound actively smokes. Considering the caustic nature of the vapors, they work with the heroine of the article only in laboratory conditions. Usually, hydrogen sulfide and iodine are taken. The following reaction is obtained: H 2 S + I 2 à S + 2HI. Elementary, formed as a result of interaction, precipitates.

The reagent can also be obtained by combining a suspension of iodine, water and sulfur oxide. The result will be sulfuric acid and the heroine of the article. The reaction equation looks like this: I 2 + SO 2 + 2H 2 O à 2HI + H 2 SO 4.

The third way to obtain hydrogen iodide is by combining potassium iodite and. The output, in addition to the heroine of the article, will be potassium hydrogen orthophosphate. Hydrogen iodide is released in the form of a gas in all reactions. They catch it with water, obtaining a solution. The tube through which the gas flows must not be lowered into the liquid.

At large enterprises, hydrogen iodide is produced by the reaction of iodine with hydrazine. The latter, like the heroine of the article, is colorless and has a strong smell. The chemical notation for the interaction looks like this: - 2I 2 + N 2 H 4 à4HI + N 2 . As you can see, the reaction produces a greater “release” of hydrogen iodide than laboratory methods.

There remains an obvious, but unprofitable option - the interaction of pure elements. The complexity of the reaction is that it occurs only when heated. In addition, equilibrium is quickly established in the system.

This prevents the reaction from reaching completion. Equilibrium in chemistry is the point when a system begins to resist influences on it. So, combining elemental iodine and hydrogen is only a chapter in chemistry textbooks, but not a practical method.

Application of hydroiodic acid

Like others, hydroiodic acid – electrolyte. The heroine of the article is capable of breaking up into ions through which current “runs.” For this run, you need to place the cathode and anode in the solution. One is charged positively, the other negatively.

The resulting resources are used in capacitors. Electrolytes are used as current sources and as a medium for gilding, silvering metals and applying other coatings to them.
Industrialists also take advantage of the restorative properties of hydrogen iodide. Strong is purchased for organic syntheses. Thus, alcohols are reduced by hydrogen iodide to alkanes. These include everyone . The heroine of the article also reduces halides and others to alkanes.

Only some chlorine derivatives cannot be reduced with hydrogen iodide. Considering this, few people are sad. If in the laboratory hydroiodic acid was neutralized, which means the enterprise is well financed. Let's take a look at the price tags for the reagent.

Price of hydroiodic acid

For laboratories, hydrogen iodide is sold in liters. Store the reagent in the dark. When exposed to light, the liquid quickly turns brown and disintegrates into water and diodoiodate. The container is tightly closed. The heroine of the article does not corrode plastic. This is where the reagent is stored.

57 percent is in demand. It is rarely found in warehouses; it is manufactured mainly for . The price tag is usually set in euros. In translation, it turns out to be no less than 60,000. In euros, this is 1,000. Therefore, they purchase the reagent as needed. If there is an alternative, take it. Hydroiodine is not only the strongest, but also the most expensive.

Hydrogen iodide

Hydrogen iodide
Are common
Systematic name	Hydrogen iodide
Chemical formula	HI
Rel. molecular weight	127.904 a. eat.
Molar mass	127.904 g/mol
Physical properties
Density of matter	2.85 g/ml (-47 °C) g/cm³
Condition (standard condition)	colorless gas
Thermal properties
Melting temperature	–50.80 °C
Boiling temperature	–35.36 °C
Decomposition temperature	300 °C
Critical point	150.7 °C
Enthalpy (st. conv.)	26.6 kJ/mol
Chemical properties
pKa	- 10
Solubility in water	72.47 (20°C) g/100 ml
Classification
CAS number

Hydrogen iodide HI is a colorless, asphyxiating gas that smokes strongly in air. Unstable, decomposes at 300 °C.

Hydrogen iodide is highly soluble in water. It forms an azeotrope boiling at 127 °C with a HI concentration of 57%.

Receipt

In industry, HI is obtained by the reaction of I 2 with hydrazine, which also produces N 2:

2 I 2 + N 2 H 4 → 4 HI + N 2

In the laboratory, HI can also be obtained using the following redox reactions:

H 2 S + I 2 → S↓ + 2HI

Or by hydrolysis of phosphorus iodide:

PI 3 + 3H 2 O → H 3 PO 3 + 3HI

Hydrogen iodide is also produced by the interaction of simple substances H 2 and I 2. This reaction occurs only when heated and does not proceed to completion, since equilibrium is established in the system:

H 2 + I 2 → 2 HI

Properties

An aqueous solution of HI is called hydroiodic acid(colorless liquid with a pungent odor). Hydroiodic acid is the strongest acid. Salts of hydroiodic acid are called iodides.

Hydrogen iodide is a strong reducing agent. When standing, the aqueous solution of HI turns brown due to its gradual oxidation by atmospheric oxygen and the release of molecular iodine:

4HI + O 2 → 2H 2 O + 2I 2

HI is capable of reducing concentrated sulfuric acid to hydrogen sulfide:

8HI + H 2 SO 4 → 4I 2 + H 2 S + 4H 2 O

Like other hydrogen halides, HI adds to multiple bonds (electrophilic addition reaction):

HI + H 2 C=CH 2 → H 3 CCH 2 I

Application

Hydrogen iodide is used in laboratories as a reducing agent in many organic syntheses, as well as for the preparation of various iodine-containing compounds.

Literature

• Akhmetov N.S. "General and inorganic chemistry" M.: Higher School, 2001

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See what “hydrogen iodide” is in other dictionaries:

See Iodine...

C2H5I iodide E., liquid, boiling point 72.34°; D14.5 = 1.9444. Freshly prepared iodide E. is colorless, turns brown when standing and decomposes with the release of free iodine. Has a strong ethereal odor. Difficult to light. Lit,... ... Encyclopedic Dictionary F.A. Brockhaus and I.A. Efron

- (chemical) one of the elements of the halogen group, chemical symbol J, atomic weight 127, according to Stas 126.85 (O = 16), discovered by Courtois in 1811 in the mother brine of seaweed ash. Its nature as an element was established by Gay Lussac and is closer to him... ... Encyclopedic Dictionary F.A. Brockhaus and I.A. Efron

- (also methyl hydrogen, formene) saturated hydrocarbon of composition CH4, the first member of the series СnН2n+n, one of the simplest carbon compounds around which all the others are grouped and from which they can be produced through the substitution of atoms... ... Encyclopedic Dictionary F.A. Brockhaus and I.A. Efron

Alchemists accepted that metals are complex bodies, consisting of spirit, soul and body, or mercury, sulfur and salt; by spirit, or mercury, they did not understand ordinary mercury, but volatility and metallic properties, for example, shine, malleability; under the gray (soul)… … Encyclopedic Dictionary F.A. Brockhaus and I.A. Efron

The phenomena of chemical equilibrium cover the area of ​​incomplete transformations, i.e., such cases when the chemical transformation of a material system is not completed, but stops after part of the substance undergoes a change. IN… … Encyclopedic Dictionary F.A. Brockhaus and I.A. Efron

- (chemical; Phosphore French, Phosphor German, Phosphorus English and Lat., whence the designation P, sometimes Ph; atomic weight 31 [In modern times, the atomic weight of Ph. has been found (van der Plaats) to be: 30.93 by restoration with a certain weight of F. metal... ... Encyclopedic Dictionary F.A. Brockhaus and I.A. Efron

- (chemical). This is the name given to four elementary bodies located in the seventh group of the periodic table of elements: fluorine F = 19, chlorine Cl = 3.5, bromine Br = 80 and iodine J = 127. The last three are very similar to each other, and fluorine stands somewhat apart. … … Encyclopedic Dictionary F.A. Brockhaus and I.A. Efron

Or halogens (chemical) So, these are the names of four elementary bodies located in the seventh group of the periodic table of elements: fluorine F = 19, chlorine Cl = 3.5, bromine Br = 80 and iodine J = 127. The last three are very similar to each other , and fluorine costs a little... ... Encyclopedic Dictionary F.A. Brockhaus and I.A. Efron

Limit hydrocarbon C2H4; found in nature, in secretions from the soil of oil-bearing areas. Artificially obtained for the first time by Kolbe and Frankland in 1848 by the action of potassium metal on propionitrile, and by them in the following 1849... ... Encyclopedic Dictionary F.A. Brockhaus and I.A. Efron

Acids can be classified based on different criteria:

1) The presence of oxygen atoms in the acid

2) Basicity of acid

The basicity of an acid is the number of “mobile” hydrogen atoms in its molecule, capable of being split off from the acid molecule during dissociation in the form of hydrogen cations H +, and also replaced by metal atoms:

4) Solubility

5) Stability

7) Oxidizing properties

Chemical properties of acids

1. Ability to dissociate

Acids dissociate in aqueous solutions into hydrogen cations and acid residues. As already mentioned, acids are divided into well-dissociating (strong) and low-dissociating (weak). When writing the dissociation equation for strong monobasic acids, either one right-pointing arrow () or an equal sign (=) is used, which shows that such dissociation is virtually irreversible. For example, the dissociation equation for strong hydrochloric acid can be written in two ways:

or in this form: HCl = H + + Cl -

or in this way: HCl → H + + Cl -

In essence, the direction of the arrow tells us that the reverse process of combining hydrogen cations with acidic residues (association) practically does not occur in strong acids.

In case we want to write the dissociation equation of a weak monoprotic acid, we must use two arrows in the equation instead of the sign. This sign reflects the reversibility of the dissociation of weak acids - in their case, the reverse process of combining hydrogen cations with acidic residues is strongly pronounced:

CH 3 COOH CH 3 COO — + H +

Polybasic acids dissociate stepwise, i.e. Hydrogen cations are separated from their molecules not simultaneously, but one by one. For this reason, the dissociation of such acids is expressed not by one, but by several equations, the number of which is equal to the basicity of the acid. For example, the dissociation of tribasic phosphoric acid occurs in three steps with the alternating separation of H + cations:

H 3 PO 4 H + + H 2 PO 4 —

H 2 PO 4 - H + + HPO 4 2-

HPO 4 2- H + + PO 4 3-

It should be noted that each subsequent stage of dissociation occurs to a lesser extent than the previous one. That is, H 3 PO 4 molecules dissociate better (to a greater extent) than H 2 PO 4 - ions, which, in turn, dissociate better than HPO 4 2- ions. This phenomenon is associated with an increase in the charge of acidic residues, as a result of which the strength of the bond between them and positive H + ions increases.

Of the polybasic acids, the exception is sulfuric acid. Since this acid dissociates well in both stages, it is permissible to write the equation of its dissociation in one stage:

H 2 SO 4 2H + + SO 4 2-

2. Interaction of acids with metals

The seventh point in the classification of acids is their oxidizing properties. It was stated that acids are weak oxidizing agents and strong oxidizing agents. The vast majority of acids (almost all except H 2 SO 4 (conc.) and HNO 3) are weak oxidizing agents, since they can only exhibit their oxidizing ability due to hydrogen cations. Such acids can oxidize only those metals that are in the activity series to the left of hydrogen, and the salt of the corresponding metal and hydrogen are formed as products. For example:

H 2 SO 4 (diluted) + Zn ZnSO 4 + H 2

2HCl + Fe FeCl 2 + H 2

As for strong oxidizing acids, i.e. H 2 SO 4 (conc.) and HNO 3, then the list of metals on which they act is much wider, and it includes all metals before hydrogen in the activity series, and almost everything after. That is, concentrated sulfuric acid and nitric acid of any concentration, for example, will oxidize even low-active metals such as copper, mercury, and silver. The interaction of nitric acid and concentrated sulfuric acid with metals, as well as some other substances, due to their specificity, will be discussed separately at the end of this chapter.

3. Interaction of acids with basic and amphoteric oxides

Acids react with basic and amphoteric oxides. Silicic acid, since it is insoluble, does not react with low-active basic oxides and amphoteric oxides:

H 2 SO 4 + ZnO ZnSO 4 + H 2 O

6HNO 3 + Fe 2 O 3 2Fe(NO 3) 3 + 3H 2 O

H 2 SiO 3 + FeO ≠

4. Interaction of acids with bases and amphoteric hydroxides

HCl + NaOH H 2 O + NaCl

3H 2 SO 4 + 2Al(OH) 3 Al 2 (SO 4) 3 + 6H 2 O

5. Interaction of acids with salts

This reaction occurs if a precipitate, gas, or a significantly weaker acid is formed than the one that reacts. For example:

H 2 SO 4 + Ba(NO 3) 2 BaSO 4 ↓ + 2HNO 3

CH 3 COOH + Na 2 SO 3 CH 3 COONa + SO 2 + H 2 O

HCOONa + HCl HCOOH + NaCl

6. Specific oxidative properties of nitric and concentrated sulfuric acids

As mentioned above, nitric acid in any concentration, as well as sulfuric acid exclusively in a concentrated state, are very strong oxidizing agents. In particular, unlike other acids, they oxidize not only metals that are located before hydrogen in the activity series, but also almost all metals after it (except platinum and gold).

For example, they are capable of oxidizing copper, silver and mercury. However, one should firmly grasp the fact that a number of metals (Fe, Cr, Al), despite the fact that they are quite active (available before hydrogen), nevertheless do not react with concentrated HNO 3 and concentrated H 2 SO 4 without heating due to the phenomenon of passivation - a protective film of solid oxidation products is formed on the surface of such metals, which does not allow molecules of concentrated sulfuric and concentrated nitric acids to penetrate deep into the metal for the reaction to occur. However, with strong heating, the reaction still occurs.

In the case of interaction with metals, the obligatory products are always the salt of the corresponding metal and the acid used, as well as water. A third product is also always isolated, the formula of which depends on many factors, in particular, such as the activity of metals, as well as the concentration of acids and the reaction temperature.

The high oxidizing ability of concentrated sulfuric and concentrated nitric acids allows them to react not only with practically all metals of the activity series, but even with many solid non-metals, in particular with phosphorus, sulfur, and carbon. The table below clearly shows the products of the interaction of sulfuric and nitric acids with metals and non-metals depending on the concentration:

7. Reducing properties of oxygen-free acids

All oxygen-free acids (except HF) can exhibit reducing properties due to the chemical element included in the anion under the action of various oxidizing agents. For example, all hydrohalic acids (except HF) are oxidized by manganese dioxide, potassium permanganate, and potassium dichromate. In this case, halide ions are oxidized to free halogens:

4HCl + MnO 2 MnCl 2 + Cl 2 + 2H 2 O

16HBr + 2KMnO 4 2KBr + 2MnBr 2 + 8H 2 O + 5Br 2

14НI + K 2 Cr 2 O 7 3I 2 ↓ + 2Crl 3 + 2KI + 7H 2 O

Among all hydrohalic acids, hydroiodic acid has the greatest reducing activity. Unlike other hydrohalic acids, even ferric oxide and salts can oxidize it.

6HI ​​+ Fe 2 O 3 2FeI 2 + I 2 ↓ + 3H 2 O

2HI + 2FeCl 3 2FeCl 2 + I 2 ↓ + 2HCl

Hydrogen sulfide acid H 2 S also has high reducing activity. Even an oxidizing agent such as sulfur dioxide can oxidize it.